How Even Short Interruptions Can Derail Your Train of Thought

The problem of interruptions at work

In his TED Talk on the topic, Jason Fried concluded that one major reason for not getting things done is being interrupted too often. A recent study by researchers from Michigan State University now underscores this conclusion: even momentary interruptions or distractions double, sometimes even triple the number of mistakes made while performing a task.

Erik M. Altmann and David Z. Hambrick from Michigan State University and J. Gregory Trafton from Naval Research Center Laboratory in Washington used quite a smart task to identify different effects of the interruptions on task performance. Study participants were to identify certain features of a character presented to them on a screen and had to stick to a certain order of steps while doing the identification task. On each screen, there was a letter and a digit, one of them in a box and one above or below the box. First, they had to determine whether the character was underlined or in italics, then whether the letter was near or far from the start of the alphabet, then whether the character was red or yellow, then whether the character was above or below the box, then whether the letter was a vowel or a consonant, then whether the digit was even or odd, and finally whether the digit was less or more than 5. Using this task, they could determine where participants made an error when interrupted. Was it in the sequence, meaning they gave the correct responses, but not in the order they were supposed to give them in? Or was the order correct, but the response was wrong? Or were both correct, and simply the response took longer? Or were there combinations of the three sources of error? Finally, the tasks also differed in their difficulty level, with for example telling the distance from the start of the alphabet being a lot more difficult than telling the colour of the character. The picture below depicts the task.

The results show that it does not take participants a lot of time to resume the task after the interruption. Furthermore, they do not make a lot more mistakes on the specific step of the task they resume. Speaking in terms of the experimental setting: They do well on the identification task after the interruption. However, they are highly likely to resume their train thought at a different point than they might have done without the interruption.

The original article will be published in the Journal of Experimental Psychology: General and can be downloaded on Erik Altmann’s homepage. There is also an outline of the study on the MSU homepage.

This reflects exactly what German time management coaches call the “Sägeblatteffekt” (saw tooth effect; however, the term does not really seem to have the same meaning in English). When we are interrupted, we need some time to get back into what we had been doing before the distraction. Thus, it takes some time until we can perform at 100% again. At the next interruption, performance plummets again, and again it takes us time to get back to 100% performance. When this happens a number of times and you look at the (imaginary) performance curve, it looks like a saw tooth.

So let’s take to heart Jason Fried’s advice once more: Introduce no talk periods where employees can work without interruption. Switch from active to passive communication by using for example email or instant messengers, and reduce the number of meetings. This will not only help you get things done, but also save you a lot of time

About the Author

Dr Katharina Lochner is the former research director for the cut-e Group which was acquired by Aon in 2017. Katharina is now a researcher and lecturer at the University of Applied Sciences Europe in Iserlohn, Germany. In her role at cut-e, she applied the research in organizational and work psychology to real-world assessment practice. She has a strong expertise in the construction and evaluation of online psychometric tools.